


i'll run when you run

by corpsesoldier



Category: Fire Emblem: Fuukasetsugetsu | Fire Emblem: Three Houses
Genre: Alternate Universe - Canon Divergence, Dark Sothis, F/F, Mind Control
Language: English
Status: In-Progress
Published: 2020-03-03
Updated: 2020-03-15
Packaged: 2021-02-23 01:13:50
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,552
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23003386
Author URL: https://archiveofourown.org/users/corpsesoldier/pseuds/corpsesoldier
Summary: When Byleth looked up, Edelgard met her eyes and felt her chest hollow, felt it fill with icy fear. It wasn’t her professor looking back.---In the Holy Tomb, the goddess was supposed to gift her chosen a revelation. But she was greedy—hungry—and instead, she took.Edelgard watched as everything she'd hoped for came to an end.
Relationships: Edelgard von Hresvelg/My Unit | Byleth
Comments: 42
Kudos: 176





	1. Chapter 1

If asked, Edelgard would have said she didn’t believe there would be any revelation in the Holy Tomb. It would be more accurate to say she hoped there wouldn’t be, that she was afraid of what such a revelation might reveal. About the Church. About the Empire. About her.

It wasn’t that she didn’t believe. The Crests and Heroes’ Relics were indisputable reality. And there was no denying the change in Byleth, her hair the color of sun-starved grass, her eyes seeming to glow. No, Edelgard believed wholeheartedly. It was the way the faith had been used, twisted into a tool of oppression, that she couldn’t support. 

She wasn’t sure there would be a difference, after tonight.

She watched Byleth ascend the steps to the Throne of Knowledge and tried to remember the last time her heart had beat this fast. Not since she was a child, she thought, chained in the dark, forced to listen to the sounds of her family suffering. Since then, fear had been bled out of her, replaced with purpose sharp and clear as glass. But watching Byleth sit on that rough hewn throne, Edelgard was afraid.

She had laid claim to her own throne not long ago, with Byleth as witness. She had offered her trust, delicate and little used, and seen Byleth consider it. Consider what it might mean. Since then, she had let herself depend on her support. Like a fool.

Why would she believe in Edelgard over the goddess herself?

For a long moment, nothing happened. Byleth met her eyes, looking unsure but not surprised, not disappointed. The Archbishop’s calm mask slipped, just an instant, and Edelgard let herself hope.

Then Byleth doubled over like she’d been struck. Her knuckles turned white, clung to the unyielding stone. Edelgard could see her shaking even from this distance. 

The worst was the scream. She had never heard her professor make a sound like that. It was torn from Byleth’s throat, like it was ripping her apart. The terrible sound echoed off the damp stone of the tomb but somehow, beneath the shattering noise, Edelgard still heard Rhea sigh.

“Finally.”

Before Edelgard could move, before she could _think_ to move, Hubert’s hand gripped her arm. Hard, harder than he would normally dare. 

“We must act now,” he hissed. His hand was the only thing stopping her from charging up those stone steps. “Your Majesty, we will not get another chance. We _must_ act.”

“This wasn’t part of the plan.” She could barely remember what the plan was. Nothing existed but that horrible scream, going on and on, longer than breath should allow.

Then it was over. Byleth slumped against the stone, breathing hard. Nobody spoke. The rest of her house cast frightened, questioning looks between Byleth and Rhea. A few even looked to her, trusting her, expecting her to decide the next move.

“ _Your Majesty_ ,” Hubert said again.

When Byleth looked up, Edelgard met her eyes and felt her chest hollow, felt it fill with icy fear. It wasn’t her professor looking back.

“Give the order,” she breathed.

There was a faint rush of magic and Hubert was gone.

Edelgard had never felt so alone. But she had cut this path, and now she must walk it.

Rhea stepped forward, her arms outstretched. “Welcome. Welcome back.” Her voice wavered with an emotion Edelgard didn’t want to consider. “I have waited so very long to receive your guidance.”

Byleth _(not Byleth, Byleth had never looked at her like that before)_ rose with a restrained dignity Edelgard had never seen, so unlike a mercenary’s lean power and fluid motion. 

“There will be time for that,” the creature said in Byleth’s voice. “But there is something we must deal with first.” Her eyes didn’t leave Edelgard and she showed her teeth, smiling like the wolf from a fairytale.

Rhea’s consideration fell on Edelgard for the first time since they had returned from the Sealed Forest. Her eyes were cold. Edelgard could sense her house’s growing unrest. She could hear, distantly, the sound of her troops approaching.

Time to walk the path.

“In the name of the Adrestian Empire,” _(how did she sound so calm?)_ “I lay claim to the Holy Tomb and all within it.” The Imperial army poured into the tomb at her back. Hubert was suddenly beside her again, and he thrust an axe into her hands. “I bid you all to stay back. I have no wish to harm you.”

The Black Eagles erupted with questions, shouts, demands for an explanation. Edelgard had none to give. She only watched Byleth’s unhurried progress down the steps. She stopped beside the Archbishop, whose face colored with indignant fury. 

“Insolence!” Rhea cried. “You will pay for the sin of defiling this place.”

Edelgard only turned to her army. “Collect the Crest stones. And if anyone attempts to stop us—” A single agonized beat of her heart. “—kill them.”

Rhea swept forward, unbowed. “Destroy these traitors who dare to dishonor you!” 

And Byleth drew the Sword of the Creator in one smooth motion, the relic thrumming with power. She was still smiling. “With pleasure,” she said.

Edelgard always knew it would come to this. But oh, how she had hoped it wouldn’t.

In the end, the battle was short and brutal. What else did she expect? Hadn’t she been on the other side of countless fights just like this one? She knew her classmates’ strength, the professor’s indomitable will. 

But she had never seen her professor fight with such single-mindedness before. With so little regard for her own safety, or the safety of her students. She soaked the Holy Tomb in Adrestian blood and barely stopped to draw breath. Edelgard would have sworn she heard her laughing.

Her soldiers were dead. She didn’t see Hubert among them, hadn’t seen him at all except for a brief glance of him locked in battle against Ferdinand, turning his lance aside with a flash of dark magic. She was alone again, kneeling in a pool of blood. There was an arrow embedded in her thigh and as she watched Byleth approach, all she could think was how awful it was she couldn’t even stand to meet her death.

The Sword of the Creator hung loose, dragging against the flagstones with every lazy step. It was covered in the gore of men and women who had trusted Edelgard, who had believed in her cause. And she believed in it still. She knew there had been no other way.

Byleth crouched before her, head tilted mockingly. “What a shame your path ended so soon, Your Majesty.” Her voice made Edelgard shudder. If she had to die here, she wished it was by her professor’s hand. Not by whatever abomination wore her face.

The thing that wasn’t Byleth grabbed Edelgard’s chin and turned her face up to meet her gaze. She sighed. “I really expected more from the frightful Flame Emperor.”

Edelgard wouldn’t beg. But she couldn’t stop her eyes filling with tears, couldn’t stop the monster seeing her weakness. She had failed in every imaginable way. 

“Very well,” Byleth said. Sounding bored. “Let’s end this.”

She gripped the hilt of her sword and started to rise. Stopped. Stood frozen, half crouched, the sword hanging limp in a trembling hand. Byleth’s whole body was shaking from strain. She blinked and her eyes were the clear blue of the sky.

She forced out a single syllable through clenched teeth. “El…”

A sob burst from Edelgard’s throat. Of course. She’d never known the professor to give up.

Haltingly, Byleth opened her shaking hand and the sword clattered to the ground. “El,” she choked out. “Run.”

But she couldn’t run, couldn’t even stand. And was she just supposed to abandon Byleth, now that she knew she was still there, still fighting? A foolish part of her, the part that wasn’t Emperor von Hresvelg, would rather die.

Time was running out. Byleth’s tremors were easing, she was losing whatever grip she had seized. Rhea—stepping down from the base of the throne where she had watched with satisfaction as Edelgard lost everything— Rhea was saying “I’ll end it myself.”

A rush of air and magic. Hubert was beside her, bleeding from one eye, his hair matted with blood. He grabbed her arm. The last thing Edelgard saw was Byleth’s eyes, luminescent green. And then they were gone.

**Notes for the Chapter:**

> You can also follow me on tumblr [here!](https://corpsesoldier.tumblr.com)


	2. Chapter 2

**Notes for the Chapter:**

> I'm so grateful for everyone's comments and kudos! This chapter is from Hubert's pov for a little outside perspective, but we'll return to our regularly scheduled El angst soon.
> 
> Also, to be clear, this is a Dark!Sothis AU. I think being dead for hundreds of years and then having to rideshare in Byleth's body would make anyone a little unhinged.

Hubert’s eyes and ears had been tracking the approaching incursion from Garreg Mach for days. Well, “incursion” was likely too strong a word. They were, by all accounts, a ragtag group plodding their way through the countryside, taking pains to avoid being seen without any of the actual skills that would keep them hidden, at least not from anyone who was really looking. But he wasn’t about to let them slip by on the strength of a few assumptions.

He had considered the possibility they were assassins, but trained killers would hopefully be a little more circumspect in their movements. The Archbishop wasn’t one to do things quietly in any case, not if there was the possibility of a highly visible victory for her holy knights.

No, there were too many of them to be spies, too few to be an invasion. And something about the reports itched at him. A nagging suspicion that he knew exactly what was headed their way. 

The only hospitable thing to do would be to greet them himself.

On his orders, the guards and spies in his employ allowed them to pass into the city with no difficulty. He guessed they would be heading toward the Imperial Palace. His associates will have herded his guests into one of the many dark alleys Enbarr boasted, and Hubert had only to wait. He took a position in a recessed doorway, cognizant of his reputation as Her Majesty’s pet demon, relishing it a little. The shadows were more welcoming if you could paint yourself as one of them.

Hubert could hear them approach from a long way off. It was like they were trying to alert every guard in the city, and wake half the citizens, too. It was a miracle they’d lasted this long. He found he was tracing the bottom edge of his eyepatch, a nervous gesture he had failed to break these past months, and forced himself to be still.

When their leader, a man by the shape of him, crossed his line of sight, Hubert didn’t hesitate. He launched himself out of the doorway, dagger drawn, and threw the man bodily against the brick wall. Blade at his throat, hand locked around one wrist, pressing his height advantage. He was gratified to hear one of the party scream.

It was the man’s hair he recognized first, bright against the darkness. Lantern light outlined the familiar, aristocratic planes of his face. Hubert felt the man recognize him in turn, felt it in the way the fight went out of him, the way his shoulders sagged.

“Hubert,” Ferdinand choked. 

Hubert snarled and pressed him harder against the wall. His pulse throbbed hot and angry where his eye should have been. 

“Hubert?” Another voice made him turn and look at the pathetic little army that had been marching across Adrestia for weeks. What he saw instead were his classmates—battered, bruised, their armor askew, their eyes hollow with hunger and exhaustion. It was Dorothea who had spoken and who was reaching out as though to soothe an animal.

Hubert didn’t remove the dagger from Ferdinand’s throat. “Give me one good reason I shouldn’t execute all of you as traitors.”

Something like mirth tugged at her lips and it infuriated him. “Because you know Bern’s a very good shot,” Dorothea said. Bernadetta jumped and fumbled for an arrow.

He whistled. There was movement at either end of the alley and on the roofs above them as guards shuffled into sight, crossbows drawn. 

“It’s been quite some time, if you’re willing to mistake me for an idiot,” Hubert hissed.

Nobody moved. Hubert realized that it wasn’t just the Black Eagles who’d come crawling back, but a handful of other students as well. He could see Leonie, bleeding from a cut along her jaw, with an arm wrapped protectively around Lysithea’s shoulders. And there was Ingrid supporting a limping Sylvain, her free hand closed around Felix’s wrist to stop him drawing his sword. 

They looked desperate. He knew the feeling.

Hubert sighed through his teeth and stepped away, dropping his hand. Ferdinand gasped like a fool—Hubert hadn’t even choked him—and doubled over. The guards relaxed their aim. The tension bled out of Hubert like ice melting, leaving him too hot at the center of that uncomfortable silence.

He felt Ferdinand’s eyes on him. Felt his attention fall on the eyepatch he couldn’t quite hide behind his hair.

“To what do I owe the pleasure?” Hubert sneered. He couldn’t stand to see pity on Ferdinand’s face. He needed to be in control.

“You were right,” Ferdinand says, straightening up. “You— Lady Edelgard was right. There is something wrong with the church. With the professor.” There was an echo of the haunted look his emperor wore in Ferdinand’s eyes. “Something has gone very wrong.”

“It wasn’t safe there,” Dorothea continued. “We brought anyone we could convince to come. To join the fight.”

The fight they were losing by bloody inches. He had fought beside these people; saints, he had fought _against_ them. The Empire needed their expertise. 

He also knew that whatever news they’d brought would likely cause Lady Edelgard more pain.

“I suppose,” he drawled, “that you’ll require an audience with the emperor.”

*

Hubert wanted his classmates to present themselves before the throne, as befitted supplicants asking for mercy, but Edelgard insisted on somewhere less formal. He managed to fit the lot of them around a long dining table in the emperor’s quarters. 

Edelgard sat at the head, Hubert at her right hand. She wasn’t asleep when he’d called upon her, which was the case more often than he liked. She would exhaust herself redrawing plans or signing orders, and on more than one occasion he had spotted her simply wandering, her white hair making her another ghost among many in the palace halls.

She demanded to meet with them at once. If her eyes were slightly bruised, her smile strained, well, he could say the same of the rest of their company. Perhaps only Hubert noticed. 

“I must admit this is something of a surprise,” she began.

It cracked the silence like an eggshell and several people started talking at once. Hubert pulled a few words from the torrent _(Rhea—Professor—kill—frightened—sorry)_ and the knot of dread in his stomach wound tighter.

Edelgard laughed. Hubert’s head snapped around so fast that he nearly overturned his coffee. 

“Please, please,” she said. “I’m anxious to hear your news, but I think we should start with one at a time.”

Another silence, less fraught, as the company glanced around at each other. Finally, Ferdinand leaned forward. “Edelgard.”

On instinct, Hubert snapped, “You will address her as Your Majesty—”

“Hubert,” Edelgard rebuked, shooting him a look that was almost pleading. She turned back to Ferdinand. “Edelgard is fine. More than fine.”

Hubert bit his tongue. In truth, she didn’t look the part of Emperor von Hresvelg. She’d refused to take any time (waste any time) adorning herself in capes or crowns. Demanded they be brought to meet her at once. Even her hair hung loose. It made her look very young.

The way Ferdinand’s face softened at Edelgard’s words completely erased any lingering suspicions Hubert had about his intentions and also made him want to pour hot tea over Ferdinand’s head.

“Edelgard,” Ferdinand continued. “You were right about the church, about Rhea. Everything has been strange since that night in the Holy Tomb. She’s done something to the professor— We’re sorry. We should have trusted you.”

Edelgard’s hands tightened where they’re folded on the table. “What happened?”

“We...were not sure, at first,” Ferdinand started.

“We didn’t want to believe,” Ingrid chimed in, her face a mask. “We knew something was wrong and chose to ignore it.”

“We thought she was just angry. With you, Edie,” Dorothea said. She looks to where Felix, Ingrid, and Sylvain sat close together. “Like Dimitri.”

Felix scoffed, but Sylvain cut him off. “Dimitri was furious. I’ve never seen him like that before.”

Dorothea continued, “We knew you and the professor were close.” Edelgard cut her eyes away from them, stared fixedly at the teapot. “It made sense for her to feel betrayed. I think we all did, a little.”

“She kept saying she would wipe out the empire entirely,” Ferdinand said. “Not just defeat it or conquer it. She wants it destroyed. And not only the Empire; anyone who ever supported the Western Church or Lonato, anyone who expressed any doubt.”

“Ashe disappeared,” Felix said. He’d barely moved since they’d sat, but now his eyes burned into Edelgard with a fierce demand. They were the first words Hubert had heard him speak since he arrived.

Edelgard closed her eyes briefly, her shoulders straight and taut as wire.

“Your Majesty,” Hubert said, hoping to forestall any more revelations. 

She held up a hand. “No. I need to understand the situation.”

“She killed Shamir!” Caspar shouted. He slammed his palm on the table, shaking with rage. He must have learned some self control over the last difficult weeks, to contain himself this long. “In the middle of the monastery, right in front of everyone. Just walked up and—” He choked. “Said she would have no more non-believers poisoning her holy order.”

The table fell silent. Blood drained from Edelgard’s face. Hubert himself froze, so as not to let his shock show. 

“Edie.” Dorothea’s voice seemed suddenly very loud. “Can you tell us what’s going on?”

Edelgard surged to her feet like she couldn’t bear to stay still any longer. She began to pace, but her voice was clear. A general addressing her troops.

“I don’t think it's Byleth.” She forged on before anyone could interrupt her. “Something’s taken control of her, possessed her. But she fought back—” A sharp breath Hubert didn’t think anyone else was close enough to hear. “She bought us enough time to escape from the Holy Tomb. She saved me.”

Hubert stepped in to give her a moment to compose herself; he could see her clenching and releasing her fists, trying to hold onto something that wasn’t there.

“We think the so-called revelation was a kind of summons. We don’t know the exact nature, but given the evidence—and the professor’s unusual appointment as our teacher—it seems likely that Rhea planned this all along.”

Edelgard stopped pacing and held herself stone still, turned away from them. It was his classmates’ turn to be shocked. He took no pleasure in it. The professor’s fate hung over all of them like a sword waiting to fall, a half-finished tragedy.

“She calls her Mother.”

Edelgard turned at once. “What?”

Ingrid met Edelgard’s wild eyes without flinching. “Rhea. I heard her call Byleth ‘Mother.’”

*

Hubert saw to it that their former classmates were given quarters. Once they had all been ushered out of the emperor’s chambers, he waited a moment. Edelgard was sitting again, her head bowed in her hands. She looked every inch a young woman with the weight of the world resting atop her.

“Your Majesty. Can I be of any service?”

She didn’t lift her head. Then, in a voice so small he almost didn’t catch it, she asked, “What are we going to do, Hubert?”

Never had he heard such naked despair in her voice. He knew she often had doubts and was adept at concealing them but, with a hot bolt of shame, he realized she had managed to fool even him.

“We have only ever had one path forward. So you’ve said yourself.”

She let out a shuddering sigh and lifted her head. “Forgive me. I am overtired. I’m not myse—” She bit off the word, her gaze sliding off of him. “I will be fine. Good night, Hubert.”

He bowed. “Your Majesty.”

He closed the door and nearly collided with Ferdinand as he turned into the hallway. He was still disheveled, like he had been waiting out here all this time. Lurking didn’t suit him.

“You should be resting.” Hubert said. “You will need to be recovered from your flight to be of any use to Lady Edelgard.”

He tried to step around him, but Ferdinand closed the distance and Hubert found he was the one with his back to a wall.

“Hubert, I—”

Ferdinand reached out. Hubert was fast, but only barely managed to catch his wrist before his fingers brushed his cheek below the eyepatch. They stood like that for a moment, Ferdinand looking dimly surprised, before Hubert threw his arm down. 

“Do not touch me.”

“Hubert, please, a moment. I am so sorry. I did not—I should not have—” His half-cocked apology died in his throat under Hubert’s glare. “Is there anything I can do?” He whispered.

“You may serve our emperor. I do not require your services.”

He turned and swept down the hallway, choosing not to concern himself over the hurt in Ferdinand’s eyes.

**Notes for the Chapter:**

> You can also follow me on tumblr [here!](https://corpsesoldier.tumblr.com)


End file.
